A segmented-mirror telescope of extremely large diameter being built at Las Campanas Observatory, Chile, by a consortium of eleven American, Australian, and Korean universities and research institutes. The GMT’s main mirror will consist of seven 8.4-m circular segments, six in a ring and the seventh at the centre, forming a collecting area equivalent to that of a single mirror 21.4 m in diameter and with the resolving power of a 24.5-m mirror. Each main-mirror segment reflects light onto one of seven secondary mirrors with adaptive optics, and the multiple light paths are combined at the Gregorian focus. The GMT consortium consists of the Carnegie Institution for Science, the University of Arizona, Harvard University, the Smithsonian Institution, the University of Texas at Austin, Texas A&M University, Korea Astronomy and Space Science Institute, the Australian National University, Astronomy Australia, the University of Chicago, and the São Paulo Research Foundation (Brazil). The GMT is planned for completion in 2024.

http://www.gmto.org/ Official telescope website.